1. Field of the Invention
This invention relates generally to high pressure sprayers and more specifically, to a high pressure sprayer indexing assembly which allows an operator to select the appropriate fluid condition by rotating the sprayer head.
2. Description of the Prior Art
The concept of sprayers with indexing nozzles is well known as indicated by the Piggot patent 3,516,611 and the Bruggeman patent 3,777,028. However, these prior art sprayers have serious shortcomings which makes them difficult to use, and in some cases, potentially hazardous to use. One of the problems of the prior art high pressure indexable sprayers is the difficulty for the operator to safety index the nozzle, i.e., select a particular nozzle. In most cases the high pressure fluid must be shut off before indexing. If the high pressure is not shut off the seals in the sprayer will be ruined during the indexing.
The cause of indexing problems with high pressure fluid is that the high pressure fluid acting on one side of the seal, partially displaces the seal from its required total confinement for indexing. Consequently, indexing results in a pinching, cutting or total destruction of the seal as the nozzle is indexed, i.e., rotated within the sprayer head. To avoid this problem, most commerical high pressure sprayers carry warnings such as "index with pressure off." Even so, indexing under pressure, whether intentional or accidental, is the most common cause of seal failure in indexing sprayers. Not only is seal destruction a problem but the destructive force of high pressure fluid stream, which may be under pressure as high as 1,000 psi., can be potentially hazardous to an operator should the operator accidentally come in contact with high pressure stream of fluid. Consequently, some indexing sprayers have provided bleed ports in the event of seal failure to ensure high pressure fluid is directed away from the operator.
An improvement to the state of the art is shown in the Arthur A. Anderson U.S. Pat. No. 3,982,698 which shows two nozzles each having a seal therearound. Both nozzles are located on the end face of a cup-shaped circular head which is rotatably mounted and held on the body of the sprayer by a threaded cap. A fluid passage for supplying high pressure fluid is located in line with the set of nozzles. A further seal comprising an O ring and a pair of thrust washers is located around the body of the sprayer and between a ridge in the body of the sprayer in the back of the threaded cap. The thrust washers allow rotation of the head in the threaded cap with respect to the sprayer body. The O ring seals the high pressure fluid within the sprayer. A set of resilient seals which are located coaxially around the inlet of each of the nozzles have high pressure fluid on both sides of the seal so that the seals are not under any fluid pressure which would force the seals out of the groove. Thus, this improvement to the prior art shows the feature of the pressure being equalized on both sides of the seal so the nozzle can be indexed without fear of destroying the nozzle seals. The present invention provides the further improvement of providing a nozzle which can be safely indexed under high pressure without destroying the seals of the unit.